Predictable yet surprising

Sunday

Nov 23, 2008 at 12:01 AM

One of the joys of studying nature is its reliability. The annual events that occur with the passing seasons — bird migration, wildflower blossoming, autumn foliage and so many others — are relatively dependable.

One of the joys of studying nature is its reliability. The annual events that occur with the passing seasons — bird migration, wildflower blossoming, autumn foliage and so many others — are relatively dependable.

Those who witness and record these natural events can usually predict their arrival to within a few days from year to year. Of course, variations in the weather can cause some of these events to come earlier or later by as much as a week or two (and global warming has caused several natural events to occur earlier in some parts of the world), but even these variations can be explained and related to definite causes.

It's comforting to know that nature's seasonal happenings still come to us in a rather predictable fashion despite the drastic changes we humans have inflicted on Mother Earth.

Even though the tendency of plants and animals to behave in certain ways and adhere to certain schedules goes straight to the core of nature study, that doesn't mean there are no surprises out there. The 18 inches of snow that fell on the Pocono Plateau on Oct. 28 and destroyed countless trees was certainly unexpected.

After 30 years of watching bald eagles, I was completely unprepared for the recent sight of one plucking a road-killed gray squirrel with a backward grab of its talons while flying at great speed along Route 196.

But one of the biggest shocks came to me by mail last week from naturalist Brian Hardiman of Monroe County Environmental Education Center. Brian (who brought me to a big black bear hibernating right out in an open field a few years ago) photographed a black rat snake "basking" in the sun on Oct. 30 up on Raccoon Ridge, near Blairstown, N.J. As if that late date wasn't unusual enough, the snake was on top of the snow and the air temperature was 42 degrees F.

I've seen snakes that late in the year on previous occasions. About 15 years ago, I found a very large northern watersnake on Oct. 31 near a pond in South Sterling. I brought the snake home to measure it (48 inches) and put it in a box overnight. When I drove back to release it at the pond the next day, 35 snakes crawled out of the box — she gave birth to 34 babies overnight, explaining why this snake had delayed going into hibernation underground.

And just two weeks ago, on a mild early November day, I saw a garter snake basking in the sun in the forests of Skytop.

Neither of these sightings, however, compare with Brian's black snake in the snow on a cold November day. This shatters all of our preconceived notions of "cold-blooded" reptiles retreating underground in autumn once temperatures decline to the 50s, and remaining there until April or May.

So what's the story here? Why was this black snake on top of the snow? Maybe it was disturbed from its den and came up to the surface temporarily, only to be trapped by the sudden snowfall. Perhaps it was unable to find its den in the first place in early autumn and was wandering from rock crevice to crevice, unable to find an underground passage. Since reptiles can't survive subfreezing temperatures, this black snake is doomed if it can't find its way below the frost line.

The only local reptile sighting stranger than Brian's was experienced last winter by another prominent local naturalist, Rick Koval. While exploring the Lehigh Gorge on a January day, Rick found a newborn timber rattlesnake on a rock ledge. Female timber rattlers give birth to live young in early September, and a few weeks later they all retreat through crevices and loose rocks to underground dens until next May. Finding one above the ground in January is unprecedented and very difficult to explain.

So, part of the charm and satisfaction of studying nature is its predictability and reliability. But another reason to go out every day and explore our forests, fields and wetlands is simply the very real possibility that something completely unexpected and unexplainable may turn up.

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